水分条件对稻田土壤汞甲基化影响的模拟研究

发布时间：2018-07-16 08:47

【摘要】：通过培养实验,研究了70%田间持水量、干湿交替及淹水等3种水分管理方式对外源Hg在稻田土壤中甲基化的动态过程.外源添加浓度为5 mg·kg~(-1)Hg~(2+),培养时间为42 d.结果表明,70%田间持水量下,土壤甲基汞(Me Hg)含量基本保持稳定,平均为11.55μg·kg~(-1);淹水条件下,土壤Me Hg含量呈上升趋势,平均为30.70μg·kg~(-1),约为70%田间持水量的2.7倍;干湿交替条件下,土壤Me Hg呈现"涨-消"的波动趋势,平均含量为20.41μg·kg~(-1),约为70%田间持水量的1.7倍.培养结束后土壤Me Hg含量和占总Hg比例依次为:淹水(37.42μg·kg~(-1),0.76%)干湿交替(16.08μg·kg~(-1),0.33%)70%田间持水量(11.75μg·kg~(-1),0.25%),表明淹水条件有利于稻田土壤中汞的甲基化.Elovich方程可以拟合淹水条件下稻田土壤Me Hg含量变化的动力学过程,表明土壤中Me Hg含量在试验前期(7 d)快速升高,随后呈现缓慢增长的趋势.培养期间,各水分处理下稻田土壤中硫酸盐还原菌(SRB)数量均表现为上下波动式的周期性变化特征,均值分别为(533±31)cfu·g~(-1)(70%田间持水量)、(615±39)cfu·g~(-1)(淹水)和(509±43)cfu·g~(-1)(干湿交替).相关分析表明,土壤Me Hg含量与硫酸盐还原菌(SRB)数量、氧化还原电位(E_h)、土壤含水量之间的相关性达到了显著性水平(p0.05),与其他因素之间无显著相关性.可以推测,在稻田土壤淹水形成的厌氧环境中,SRB可能是生物汞甲基化的优势菌群.
[Abstract]:The dynamic process of methylation of exogenous Hg in paddy soil by three water management methods, I. e., 70% field water holding capacity, alternate dry and wet water and flooding, was studied by culture experiments. Exogenous concentration was 5 mg kg-1 Hg2, culture time was 42 days. The results showed that under 70% field water holding capacity, the content of methyl mercury (me Hg) in soil remained stable, with an average of 11.55 渭 g kg ~ (-1), while under flooding, the content of me Hg increased, with an average of 30.70 渭 g kg ~ (-1), about 2.7 times of 70% field water holding capacity. The average content of me Hg was 20.41 渭 g kg ~ (-1), which was 1.7 times of that of 70% field water holding capacity. After the end of culture, the content of me Hg and the proportion of total Hg in soil were as follows: flooding (37.42 渭 g kg ~ (-1) 0.76%), alternating dry and wet (16.08 渭 g 路kg ~ (-1) ~ (-1), 70% field water holding capacity (11.75 渭 g 路kg ~ (-1) ~ (-1) ~ (-1) ~ (-1), which indicated that flooding condition was beneficial to the methylation of mercury in paddy soil. Elovich equation could fit the equation of mercury methylation in paddy soil under flooded condition. The kinetic process of the change of me Hg content, The results showed that the content of me Hg in soil increased rapidly at the early stage of the experiment (7 days) and then slowly increased. During the incubation period, the number of sulfate reducing bacteria (SRBs) in paddy soils showed a fluctuating periodicity, with the mean values of (533 卤31) cfu g-1 (70%), (615 卤39 cfu g-1 (flooding) and (509 卤43) cfu g-1 (dry-wet alternating), respectively. Correlation analysis showed that the correlation between the content of me Hg and the amount of sulfate reducing bacteria (SRB), the redox potential (Etih) and the soil water content was significant (p0.05), but there was no significant correlation between the content of ME Hg and other factors. It can be inferred that SRB may be the dominant microflora of mercury methylation in anaerobic environment formed by flooded paddy soil.
【作者单位】：农业部农业生态与资源保护总站;农业部环境保护科研监测所;
【基金】：国家自然科学基金(No.41203084,41371463) 国家水体污染控制与治理科技重大专项(No.2015zx07103-007) 国家重点研发计划(No.2016YFD0201306)~~
【分类号】：X53

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